In a synchronous direct-sequence code division multiple access (S-CDMA) system, users communicate simultaneously using the same frequency band via orthogonal modulation or spread spectrum.
Reference with regard to a CDMA waveform can be made to P. Stephenson, T. Giallorenzi, J. Harris, L. Butterfield, M. Hurst, D. Griffin and R. Thompson, U.S. Pat. No. 5,966,373, Waveform And Frame Structure For A Fixed Wireless Loop Synchronous CDMA Communications System, issued Oct. 12, 1999.
This commonly assigned U.S. Patent discloses a method and a system for transmitting information in a CDMA communication system. In the method there are steps of (a) multiplexing data and control information into a data stream; (b) encoding the data stream to form a stream of encoded I/Q symbol pairs; (c) inserting synchronization information into the stream of encoded I/Q symbol pairs; and (d) spreading the encoded I/Q symbol pairs and the inserted synchronization information using a same pseudonoise (PN) spreading code prior to transmission as a frame. The multiplexing step forms a data stream having data fields composed of a plurality of data bytes separated by control message fields. Each of the control message fields is a single byte of a control message frame. The control message frame includes a control message header field, a number of control data fields, and a plurality of data integrity fields.
More particularly, the frame includes an unencoded synchronization field followed by a plurality of data fields that each contain the data bytes. Individual ones of the data fields are separated by one of the control message fields, that in turn are composed of a single byte of the multi-byte control message frame.
The encoder operates to rate 1/2 convolutionally encode the data stream to form an I channel and a Q channel; and to then rate 4/5 puncture trellis code the I and Q channels.
While well suited for its intended purpose, advances and recent developments and requirements in the field of CDMA communication have brought about the need for an improved CDMA waveform. This need is met by the CDMA waveform in accordance with the teachings of this invention, as described in detail below.